Preliminary outcomes of intraoperative cartilage thickness measurement in kinematically aligned robot- assisted total knee arthroplasty

Purpose: This study aimed to assess the preliminary outcomes of the intraoperative cartilage thickness measurement in kinematically aligned robot-assisted total knee arthroplasty (TKA). Methods: : Patients who underwent kinematically aligned robot-assisted TKA were included in this study. Three-point cartilage thickness measurement was performed from the intact distal femoral cartilage by a digital caliper intraoperatively in order to detect the actual cartilage thickness of the patient. Hip-knee-ankle angle (HKA), mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibial angle (mMPTA), joint-line orientation angle (JLOA), and joint-line convergence angle (JLCA) were measured through standing full-length anteroposterior radiographs. Knee Injury and Osteoarthritis Outcome Score, Oxford score, VAS pain and satisfaction score, and Forgotten Joint Score were used to assess clinical outcomes. Results: : A total of 142 knees of 109 patients (92 females and 17 males) were evaluated in this study. The mean cartilage thickness was 1.9 ± 0.5 mm, 2.2 ± 0.6 mm, and 2.0 ± 0.5 mm from anterior to posterior respectively (p = 0.006). There was a significant correction in HKA, JLCA, and mMPTA postoperatively (p = <0.001, <0.001, and 0.029, respectively). We observed no significant change in mLDFA and JLOA measurements. All clinical scores significantly increased at the latest follow-up. Conclusion: Our results demonstrated that distal lateral femoral cartilage thickness varied among patients and also differed in the different regions of the condyle. Cartilage thickness measurement technique in kinematically aligned robot-assisted TKA demonstrated no significant change in mLDFA and JLOA, but significantly corrected HKA, mMPTA, and JLCA.